The evolutionary origin of "floral quartets" clues from molecular interactions of orthologues of floral homeotic proteins from the gymnosperm Gnetum gnemon
Dissertation, Friedrich-Schiller-Universität Jena, 2010
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| Sprache: | eng |
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Jena
2010
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Tag hinzufügen | Zusammenfassung: | Dissertation, Friedrich-Schiller-Universität Jena, 2010 The identity of floral organs in angiosperms is specified by multimeric transcription factor complexes composed of floral homeotic MADS-domain proteins that bind to specific cis-regulatory DNA-elements (‘CArG-boxes’) of their target genes, thus constituting floral quartets. Gymnosperms possess orthologues of floral homeotic genes enconding MIKC-type MADS-domain proteins, but when and how the interactions constituting floral quartets were established during evolution has remained unknown. To better understand the ‘abominable mystery’ of flower origin, in this project a comprehensive study was carried out to detect the dimerization and DNA-binding of several classes of MADS-domain proteins from a gymnosperm, Gnetum gnemon of the Gnetales. Determination of protein-protein interactions by pull-down assays revealed complex patterns of heterodimerization among orthologues of class B, class C and class E floral homeotic proteins and Bsister proteins, while homodimerization was not observed. In contrast, electrophoretic mobility shift assays (EMSAs) revealed that all proteins tested except one bind to CArG-boxes also as homodimers, suggesting that homodimerization is relatively weak, but facilitated by DNA-binding. Proteins able of DNA-based homodimerization include orthologues of class B and C proteins; B and C proteins also form heterodimers in vitro and in yeast, which is in sharp contrast to their orthologues from angiosperms, which require class E floral proteins to ‘glue’ them together in multimeric complexes. |
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| Beschreibung: | 72, IV Bl. Ill., graph. Darst. 29,4 cm 1 CD-ROM |